1. Field of the Invention
The present invention relates generally to the field of bicycle accessories and more particularly to the field of bicycle tire levers for removing and installing bicycle tires or the tubes thereof.
2. Prior Art
Bicycle tire levers are typically made in the same way, namely a three pack of about 4.5 inch.times.0.6 inch.times.0.3 inch each plastic pieces with a partial hook at one end for prying under the bead of the tire and a notch at the other end for catching under a spoke.
There are several reasons for having to remove and install tires. Leaking tubes can be caused by foreign matter poking a hole through the tire and tube, by "pinch flats" where the tube becomes pinched between the tire and rim during a hard impact with an object on the road, a defective or broken tube valve stem, or age; the tire is damaged; the rider wants a different tire for different riding conditions; the rider wants a different tube for different riding conditions (lighter for racing or more heavy duty for rough terrain).
The need to change the tire because of a leaking tube often occurs while in remote locations. In these situations, convenience and speed are particularly important, especially if in a race, bad weather, the dark, or a dangerous location (such as in high crime or heavy traffic areas). Most riders carry tire levers, a pump, and a spare tube or patch kit to handle these situations.
Most bicycle wheels consist of a hub with axle, spokes for connecting the hub to the rim, a C-channel rim, an expandable tube with valve stem, and a tire that has a strip of wire on each side called the bead. The bead is made of a material such as steel wire or Kevlar that strongly resists being stretched. It is mainly the two beads that retain the tire to the rim by catching under a lip on the rim and by not easily stretching. It is also primarily the bead that makes changing a tire rather difficult because it must be stretched over the rim for removal or installation. The axle is connected to the hub and the bicycle fork or frame by either nuts or quick release axle skewers. In either case, the nuts or axles skewers are normally loosened but not removed in order to remove the wheel from the bicycle.
Generally, the higher the air pressure rating of the tire, the stronger and less stretchable and tighter the fit of the bead of the tire to the rim of the wheel. This is because higher air pressure exerts greater force into pushing the tire off of the rim. As a consequence, the higher the pressure rating of the tire, the more difficult it is to remove and install the tire. Generally the first part of removing the bead and the last part of installing the bead is the most difficult because this is where the bead must be stretched the most.
Changing or repairing a tube requires the following steps: Loosen the axle nuts or quick release skewer and remove the wheel from the bicycle; release all air from the tube (if any remains); pry one bead off the rim (currently people use one, two, or three tire levers depending on how difficult the bead is to remove--current levers are designed to have one end wedged under the bead of the tire and then the lever is rotated until the other end can catch under a spoke which allows the user to have two hands to use the next lever); remove the tube by reaching between the rim and the tire (which still has one bead on the rim); the other bead is not necessary to remove from the rim unless the tire is to be replaced; patch the tube (if necessary--inflate the tube slightly to create its tubular shape); replace the slightly air-filled, repaired or new tube between the rim and the tire; push the bead back onto the rim being careful to not pinch the tube (currently people use their hands as far as possible and then use one, two, or three tire levers to finish depending on how difficult the bead is to install); fully inflate the tube to the rated tire pressure; reinstall the wheel to the bicycle and tighten the axle nuts or quick release skewer.
Changing the tire requires the following steps: Loosen the axle nuts or quick release skewer and remove the wheel from the bicycle; release all air from the tube (if any remains); pry one bead off of the rim (currently people use one, two, or three tire levers depending on how difficult the bead is to remove; pry the other bead off of the rim; push one bead of the new tire onto the rim (currently people use their hands as far as possible and then use one, two or three tire levers to finish depending on how difficult the bead is to install); push the other bead back onto the rim being careful to avoid pinching the tube; fully inflate the tube to the rated tire pressure; reinstall the wheel to the bicycle.
The two most difficult and often most time consuming steps of changing a tube or tire are prying the bead off the rim and then pushing the bead back onto the rim. In fact, it is so difficult to push the bead of some high pressure tires back on a rim that some people will choose to use a lower pressure tire even though this increases rolling resistance. Some high pressure tires can require as much as 10 minutes or more of intense effort to remove the bead from the rim and then reinstall it, even by someone skilled in the art. Even lower pressure tires usually require a few minutes to remove and install the bead. Furthermore, every time a tire lever end is wedged under the bead and then pried, there is a chance of pinching the tube causing a new leak. Current tire levers often require repeatedly wedging the lever under the bead and prying. Changing a high pressure tire could easily require 10 instances of this. It is particularly frustrating to repair a tube and then discover a new leak caused by the tire lever.
One technique for removing a bead from a rim is to pull the tire lever along the rim after prying it under the bead. In this way the bead is peeled off the rim. This sometimes works for low pressure tires but is very difficult with high pressure tires because the lever usually slips out from under the bead. It can be painful when the lever slips from under the bead because the person's hand often impacts spokes or other hard objects. The slipping is likely because it is difficult to push or pull hard on the lever while keeping the lever aligned along the rim. This sliding technique is not currently used for installing a bead because current lever design does not allow it. Current tire levers have a partial hook at one end. This same hook is used for both removing and installing a tire bead onto the rim. This hook is particularly unsuited for installing the tire bead.